1. Field of the Invention
The invention relates to an SCR injection.
2. Description of the Prior Art
It is known, for example from DE 103 24 482 A1, that the nitrogen oxide content in the exhaust of an internal combustion engine can be reduced by means of a selective catalytic reduction (SCR). To accomplish this, a substance with an immediate reducing action such as ammonia or a precursor is supplied into the exhaust and releases reducing substances once it comes into contact with the exhaust. For example, a urea/water solution can be used as a precursor. Ammonia is converted into molecular nitrogen and water in the selective catalytic reduction with nitrogen monoxide and nitrogen dioxide. The selective catalytic reduction takes place in an SCR catalytic converter.
The urea/water solution, for example, is introduced into the exhaust by means of an SCR injection unit. This injection unit in turn includes an injector and a fastening device that serves to fasten the injector to a flange of an exhaust pipe. In this way, the injector injects the urea/water solution directly into the exhaust pipe, upstream of the SCR catalytic converter.